Multifunctional Ionic liquids Coatings for Dental Implant Surfaces Abstract Titanium dental implants are known for their high success rates and adequate osseointegration in vivo. However, with an increasing number of implants used, higher incidence of implant complications and failures have been recently reported. Implant failure is classified either as early or late stage failure. Early stage failure occurs when osseointegration is not achieved typically due to bacterial contamination, premature loading, excessive surgical trauma and impaired healing. Late stage failure occurs when implant osseointegration is lost having common etiological factors associated with bacterial-induced bone loss causing peri-implantitis, and excessive occlusal stresses. Recently, corrosion has also been considered a phenomenon underlying surface integration and performance. Bacteria seem to be key players in both early and late stage failures, with their presence influencing the establishment and loss of osseointegration. Hence, the success or failure of a dental implant can be related to its surface integration with soft and bone tissues versus biofilm adhesion. Early bacterial colonizers forming biofilms can impair soft tissue sealing by infiltrating and interrupting the process of surface integration. Current surface treatment techniques for dental implants typically aim to improve only one aspect of the problem, such as prevention of infection, promotion of osseointegration, or corrosion protection. However, to improve implant function, it is crucial to prevent early bacterial adhesion and to promote a permissive environment for tissue integration. In order to achieve multi-functionalities on implant surfaces, the goal of this proposal is to develop a new generation of coatings using ionic liquid (IL) technology. Non-toxic dicationic imidazolium-based IL coatings were designed to confer the surface of dental implants with: (i) antimicrobial activity for mitigation of biofilm adhesion, which will enable host cells to reach and seal the surface of the implant; (ii) protection of the oxide layer at the critical initial healing phase of the implant; and (iii) improved frictional properties for implant insertion. Aim 1 will study the competition of bacteria and host cells for the surface (?race for the surface?) of IL coated versus non-coated titanium using a co-culture approach. A co-culture model will be developed with conditions of varying concentrations of host and bacterial cells to test both peri-operative and post-operative models. In Aim 2, implants coated with the best-performing IL, as verified in Aim 1, will be investigated in an animal model. The effect of IL coating on the associated inflammatory response, soft and bone tissues, osseointegration, and bacterial load will be assessed at different time points simulating early and late healing periods. In vivo testing will enable observation of inflammatory responses and kinetics of bone growth triggered by the presence of IL- coated surfaces in comparison to non-coated implants. This new generation of coatings aims to mitigate bacteria adhesion on the surface following implantation while providing suitable surface conditions for tissue integration. Considering current surface treatments available, the proposed IL-coating may constitute a more potent strategy to improve dental implant surfaces.